U.S. Pat. No. 4,021,040 to Inoue discloses adjustable-weight dumbbells equipped with a grip promoting member at the grasping portion thereof. The grip includes a spring and is mounted in a cantilevered manner to the handle; the dumbbell is grasped in the hand, swung vertically and horizontally for muscular strength training centering around the arm, with grip enforcement being obtained by grasping and squeezing the grip promoting unit against its springing force.
U.S. Pat. No. 4,623,141 to Salvino discloses an improvement on the conventional coil-type hand-held grip enhancing devices. The improvement disclosed by the Salvino patent resides in the provision of means for varying the resistance in the coiled spring by means of an axial rod, washers and wing nuts. U.S. Pat. No. 4,557,479 to Guibert discloses an articulated manual exercise bar designed, not to strengthen the grip, but to enable a user to execute highly complex isotonic exercise of the arms. U.S. Pat. No. 4,623,146 to Jackson discloses a similar exercise device to that of Guibert, without articulations, in that the bar enhances isotonic exercises and is held in both hands for use. U.S. Pat. No. 2,263,135 to Johnson, No. 2,356,260 to Maxwell and No. 2,814,491 to Proctor represent exercise devices from the earlier patented literature.
In view of the failure of prior art hand-held weighted exercise devices to provide both weight and leverage advantages during body conditioning, other than the augmentation of the weight of the hands, a need persists for a hand-held weighted exercise device which makes use of the leverage advantages of muscle training so commonly found in studio fitness systems.